_STD -> _VSTD to avoid macro clash on windows

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@134190 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index a943274..b138510 100644
--- a/include/__config
+++ b/include/__config
@@ -169,7 +169,7 @@
 // Inline namespaces are available in Clang regardless of C++ dialect.
 #define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {inline namespace _LIBCPP_NAMESPACE {
 #define _LIBCPP_END_NAMESPACE_STD  } }
-#define _STD std::_LIBCPP_NAMESPACE
+#define _VSTD std::_LIBCPP_NAMESPACE
 
 namespace std {
   inline namespace _LIBCPP_NAMESPACE {
@@ -247,7 +247,7 @@
 
 #define _LIBCPP_BEGIN_NAMESPACE_STD namespace std { namespace _LIBCPP_NAMESPACE {
 #define _LIBCPP_END_NAMESPACE_STD  } }
-#define _STD std::_LIBCPP_NAMESPACE
+#define _VSTD std::_LIBCPP_NAMESPACE
 
 namespace std {
 namespace _LIBCPP_NAMESPACE {